Externally mixing multi-component nozzle

ABSTRACT

An externally mixing multi-component nozzle for spraying fluids with the assistance of an atomizing gas that is hot in relation to the fluids to be sprayed, said the gas particularly being steam or hot gas. The nozzle has a housing, wherein the housing has an outlet orifice for the atomizing gas, a first annular gap for fluid to be sprayed, surrounding the outlet orifice, and a second annular gap for the atomizing gas, surrounding the first annular gap, as well as a manifold. The manifold has at least one flow channel for fluid to be sprayed, from a connecting line to the first annular gap, and at least one flow channel from an atomizing gas connecting line to the outlet orifice for atomizing gas.

The invention refers to an externally mixing multi-component nozzle forspraying fluids with the aid of an atomizing gas, especially steam orhot gas, which is hot in relation to the fluids which are to be sprayed.

In many process engineering plants, through which flows a primary fluid,especially flue gas, the aim is to mix a secondary fluid, especiallywater, as homogeneously as possible into the primary fluid andfrequently also to evaporate it over the shortest distance. For thispurpose, two-component nozzles are frequently used. In thesetwo-component nozzles, the fluid is atomized by means of a gaseous orvaporous auxiliary medium. These two-component nozzles are distinguishedby a particularly fine droplet spectrum and also by a very good partialload behavior. In many plants, especially in power plants and wasteincineration plants, steam is made available. It can then be sensible,for cost reasons, to use the steam as auxiliary atomizing medium becausethe provision of a corresponding amount of compressed air would beassociated with high investment- and operating costs.

For atomizing with two-component nozzles, two basic types of nozzle areavailable, specifically internally mixing nozzles on the one hand and,on the other hand, externally mixing nozzles. Examples of internallymixing and externally mixing nozzles are described in Nasr, Jule andBendig, Industrial Sprays and Atomization, Springer Publishing House,2002, on page 24, for example.

A spray drying nozzle, in which an atomizing gas is distributed to twoconcentric annular slots, is known from U.S. printed Pat. No. 3,770,207.An annular slot for the solution to be dried is arranged between the twoannular slots for the atomizing gas. The innermost annular slot for theatomizing gas is formed by inserting a conical piece into the centraldischarge opening.

Described in German unexamined specification DE 195 26 404 A1 is atwo-component nozzle for atomizing paste-like fluids, or fluidscontaining solids, for example slurry, in which the fluid to be atomizedis fed through a central, cylindrical passage and at the end of thispassage, by means of individual nozzles arranged in a ring-like manner,the atomizing gas is blown into the fluid to be atomized.

Described in German printed patent specification DE 85 79 24 is a dryingnozzle in which the fluid to be atomized is atomized between an innerand an outer conical flow consisting of gaseous auxiliary atomizingmedium.

With the invention, an externally mixing multi-component nozzle forspraying fluids is to be improved.

According to the invention, for this purpose provision is made for anexternally mixing multi-component nozzle for spraying fluids with theaid of an atomizing gas, especially steam of hot gas, which is hot incomparison to the fluids to be sprayed, which nozzle has a housing,wherein the housing has a discharge opening for the atomizing gas, afirst annular slot, encompassing the discharge opening, for fluid to besprayed, and a second annular slot, encompassing the first annular slot,for the atomizing gas, and also a distribution piece, wherein thedistribution piece has at least one flow passage for fluid to be sprayedfrom a connecting line to the first annular passage, and at least oneflow passage from an atomizing gas connecting line to the dischargeopening for atomizing gas.

The provision of such a distribution piece inside the nozzle housingensures that fluid to be sprayed and atomizing gas are conducted to thefirst annular slot, or to the discharge opening, and to the secondannular slot over a short distance. Just by the provision of thedistribution piece and the short distance attributable thereto, an onlylow heat transfer from fluid to be sprayed to the atomizing gas isachieved. As a result, the hot atomizing gas being able to already cooldown, and possibly even to condense, before leaving the housing can beprevented. Consequently, a much better atomizing effect is achieved. Thedistribution piece is preferably produced from solid material and theflow passages are provided inside the solid material.

In a development of the invention, the housing has an annular passagefor atomizing gas, which at least in sections encompasses thedistribution piece.

In this way, the atomizing gas can be conducted from the annular passageover a short distance into the second annular slot and, since the flowpassage of the distribution piece for the atomizing gas advantageouslyoriginates from the annular passage, the atomizing gas can also bedirected to the discharge opening over a short distance. With thepresent invention, a new-type of nozzle concept is proposed, in whichthe atomizing gas, inside a small distributor which is integrated intothe nozzle housing, is distributed to a central atomizing gas flowthrough the discharge opening and also to an outer annular slot flow. Inthis distributor, the fluid to be atomized is also apportioned to anannular slot which is arranged between the central flow and the outerannular slot flow of the atomizing gas. This distributor, or the flowpassages in the distributor, are dimensioned so that it is passed bothby fluid to be atomized and by the atomizing gas at relatively highvelocity so that hardly any time remains for heat transfer. In addition,the surfaces which lead to the heat transfer between atomizing gas andfluid are of very small dimensions and the distances between theindividual flow passages, which conduct the cold fluid and the hotatomizing gas respectively, are dimensionally as large as possible.Therefore, for construction related reasons the internal heat transferfrom the hot atomizing gas, especially steam, to the fluid to beatomized is minimized or limited to an advantageous value. A certainpreheating of the fluid can be quite advantageous because with this, inthe interests of good atomization, the surface stress and the viscosityof the fluid to be atomized can be reduced.

In the case of the invention, however, it is not exclusively a questionof atomization quality, as can be established on a virgin nozzle in thelaboratory under ideal boundary conditions. Rather, the fact that theatomization quality in industrial practice occasionally suffers from theforming of deposits inside the nozzles or at the nozzle mouth is to betaken into consideration. This especially applies when industrial wateris used as fluid to be atomized. Even if suspended matter is largelyeliminated by means of filtration, in many cases a formation of depositsin the nozzle or at the nozzle mouth as a result of the settling ofdissolved solids is to be observed. This applies above all to thosecases in which a hot atomizing gas is used, as a result of which heatingof the walls which are in contact with the industrial water can thenoccur. A limitation of the heat transfer inside the nozzle according tothe invention can consequently also solve the problem of depositsforming in the nozzle.

In a development of the invention, a thermal insulation is provided, atleast in sections, between the flow passage for fluid to be atomized inthe distribution piece and said distribution piece.

In this way, a heat transfer between the cold fluid to be atomized andthe distribution piece, which is heated by the hot atomizing gas, can bereduced.

In a development of the invention, the flow passage for fluid to beatomized in the distribution piece is formed, at least in sections, bymeans of a tube which is inserted into the distribution piece.

In this way, a heat transfer between the flow passage and thedistribution piece can already be significantly reduced. An air gap isadvantageously provided, at least in sections, between the tube and thedistribution piece. An air-gap insulation leads to a further,significant reduction of heat transfer from the cold fluid to be sprayedto the distribution piece.

In a development of the invention, the connecting line for fluid to beatomized is of double-walled design, at least in the connecting regionto the distribution piece.

In this way, a good thermal insulation, for example by means of an airgap, can be achieved between the connecting line and the housing of thenozzle.

In a development of the invention, a thermal insulation coating isprovided between the first annular slot and the housing and also betweenthe first annular slot and the second annular slot.

In this way, a heat transfer between the cold fluid and the hotatomizing gas can additionally be minimized in the annular slot regionup to the outlet of the fluid to be atomized from the nozzle. This is ofconsiderable advantage in the case of the externally mixingtwo-component nozzle according to the invention.

In a development of the invention, the discharge opening for theatomizing gas has the form of a third annular slot.

The fluid to be atomized is consequently received between two annularslot flows of the hot atomizing gas so that a very good atomizing effectis achieved. The third annular slot can be formed, for example, by theinsertion of a conical piece into the discharge opening.

In a development of the invention, the boundary of the first annularslot, as seen in the flow direction, is arranged in front of an outerboundary of the second annular slot.

In this way, the fluid to be atomized discharges from the first annularslot and comes into contact with the atomizing gas from the secondannular slot just before the atomizing gas has left the nozzle mouth atthe end of the second annular slot. The atomizing gas from the secondannular slot cannot consequently deviate to the side so that anacceleration of the fluid, which is to be atomized, by means of theflanking gas flows is carried out just before leaving the nozzle mouth.In this way, a finer atomization of the fluid to be sprayed can beachieved.

In a development of the invention, the boundary of the first annularslot is arranged by one to ten times the width of the first annular slotin front of the outer boundary of the second annular slot, as seen inthe flow direction.

In a development of the invention, at least one distribution piece isformed from a material, especially high-alloy high-grade steel, with acoefficient of thermal conductivity which is significantly reduced,especially by the factor of 8, compared with brass.

The provision of a material with low thermal conductivity for thedistribution piece can already significantly reduce a heat transferbetween the fluid to be sprayed and the hot atomizing gas.

In a development of the invention, a section—lying directly upstream ofthe discharge opening—of the flow passage for the hot atomizing gas isformed in the housing so that it first of all tapers and after passing aconstriction widens again up to the discharge opening, as seen in theflow direction.

In this way, a discharge nozzle for the atomizing gas can be ofconvergent/divergent design. In particular, this discharge nozzle can bedesigned as a Laval nozzle so that the hot atomizing gas then dischargesfrom the discharge opening at supersonic velocity.

Further features and advantages of the invention are gathered from theclaims and the subsequent description of preferred embodiments of theinvention in conjunction with the drawings. In the drawings:

FIG. 1 shows an externally mixing multi-component nozzle according tothe invention in a sectional view according to a first preferredembodiment,

FIG. 2 shows an enlarged detail of the multi-component nozzle of FIG. 1,

FIG. 3 shows a multi-component nozzle according to the inventionaccording to a second preferred embodiment, and

FIG. 4 shows a detail of a multi-component nozzle according to theinvention according to a third embodiment.

The sectional view of FIG. 1 shows a multi-component nozzle 1 accordingto the invention. In the case of the multi-component nozzle 1 accordingto the invention, the object of largely overcoming premature enthalpylosses of the atomizing gas as a result of heat transfer to the fluid tobe atomized and of preventing deposits forming in the nozzle as a resultof temperature-dependent depositing of components of the fluids whichare dissolved at low temperature, is achieved in the following way. Thesteam flow 10 which is fed via the steam feed line to themulti-component nozzle 1 is split into two partial flows in a new-typedistribution piece 18 of small dimensions which can therefore beintegrated into the nozzle 1. An outer partial flow 30 and a centralpartial flow 28 of steam or hot atomizing gas are produced. The outerpartial flow 30 is blown out via an outer annular slot 29, whereas thecentral partial flow 28 is blown out via a central nozzle 62 which endsat a discharge opening 60. An annular slot nozzle 20 for discharging thefluid to be sprayed, especially water which is to be atomized, isarranged between the central nozzle 62 having the discharge opening 60and an outer annular slot nozzle 31. The approach of atomization of thefluid via a central flow and an outer annular slot flow of the auxiliaryatomizing medium make the atomization easier. Essential for theinvention, however, is the design of the distribution piece 18 fordistributing fluid to be sprayed and hot atomizing gas to the individualdischarge openings of the nozzle 1.

A characteristic feature of the nozzle 1 is that the fluid to beatomized is not discharged via a central nozzle but via an annular slot.This annular slot can be of relatively large dimensions because in thiscase a high discharge velocity of the fluid is not necessary. Theatomization is carried out according to the invention by the fluid filmbeing introduced between two high-velocity atomizing gas flows. As aresult of the shear stress effect of these high-velocity flows, thefluid film is extracted from the annular slot to form a thin fluidlamella which disintegrates into small droplets. Therefore, the risk ofmaterial erosion on the annular slot walls of the fluid nozzle,specifically at the annular slot 21, is also greatly reduced and thelong-term stability of the throughflow characteristic of such a nozzledoes not present a problem in this respect. Such a nozzle, however, alsohas a very good partial load behavior, completely in contrast tosingle-component nozzles according to the prior art with swirlers in thefluid duct.

The central nozzle 62 for hot atomizing gas having the discharge opening60 is designed according to FIG. 1 as a convergent/divergent nozzle inthe flow direction. If, for example, steam is delivered with asupercritical pressure ratio, this configuration operates as a Lavalnozzle and the steam then discharges at supersonic velocity from thecentral nozzle 62 at the discharge opening 60. It is also important,however, that the nozzle 1 does not have an end face which is washed byindustrial water. This is achieved by the very narrowly formedboundaries of the annular slot 21. Therefore, the problem ofstalactite-like deposits, as is to be monitored in end faces of nozzlesaccording to the prior art, does not occur either in this case.

Essential features of the nozzle 1 according to the invention concernthe thermal decoupling of the hot atomizing gas, especially steam, fromthe cold water at the nozzle connection and inside the nozzle. For thispurpose, the feed line 4 for the water 5 is of double-walled design.

In addition, through-holes, via which the water 5 is fed to the annularslot 21 and the steam is fed to the central nozzle 62 having thedischarge opening 60 or to the outer annular slot 29, are arranged inthe distribution piece 18 with the greatest possible distance apart.Inserted into the holes 19 for the feed of the water to the outer partof the nozzle 1 are inner tubes 38 which on the outer side, that is tosay at their start and end, are relieved so that a wall contact, whichcenters the inner tubes 38 in the hole in the distribution piece 18,exists only in the narrow sections. As a result of this, an air-filledcavity, which serves as a thermal insulation, is created between thewater-conducting inner tube 38 and the distribution piece 18. Inaddition, the outer surface of the central nozzle 62 having thedischarge opening 60 and the inner surface of the annular slot nozzle 20having the annular slot 21 are also lined with a thermally insulatinglayer 35, 36 so that the fluid to be atomized, practically over itsentire passage through the nozzle 1 to the direct proximity of thenozzle mouth, is equipped with a thermal insulation against the nozzlehousing and especially against the distribution piece 18, and thereforealso against the flow of the hot atomizing gas. The effect achieved inthis way is that the fluid is only slightly heated, or that the hotatomizing gas, especially the hot steam, suffers only small enthalpylosses as a result of cooling.

Naturally, the possibility exists of also applying a thermal insulationon the side of the nozzle which is acted upon by steam. This, however,would usually be disproportionately costly because the surface which isin contact with the steam is significantly larger than is the case onthe water side.

A further interesting possibility is to use a material with low thermalconductivity, at least for the distribution piece 18, which material, onthe other hand, is suitable for the predetermined operating temperatureof 300° C., for example. The changeover from brass to a high-alloyhigh-grade steel already leads to a reduction of the thermalconductivity by the factor of 8.

FIG. 1, and FIG. 2 as a detail enlargement of FIG. 1, show the nozzle 1in a sectional view. The nozzle 1 is intended for being arranged insidea duct 3 which conducts a primary fluid, for example flue gas, intowhich a fluid to be atomized is to be injected. The duct 3 is onlyschematically represented by one of its boundaries. The nozzle 1 istherefore located inside the flow of the primary fluid in the duct 3.

The fluid 5 to be atomized is fed via a connecting line 4, via a centralconnection 17 of the nozzle housing 2, to the distribution piece 18 ofthe nozzle 1. Via at least one hole 19 in the distribution piece 18,into which an inner tube 38 is inserted, the fluid 5 finds its way intoan annular chamber of the annular slot nozzles 20 which inwardly isdelimited by a central nozzle piece 27 and outwardly by an intermediatecap 34. From this annulus, the fluid finds its way over the shortestdistance to the fluid outlet at the annular slot 21.

The atomizing gas, e.g. hot steam 10, is first of all fed to an annulus23 in the nozzle housing 2 via a pipe 11 which, like the connecting line4, leads out of the duct 3. From this annulus 23, the atomizing gasfinds its way into a central chamber 26 in the distribution piece 18 viaat least one milled out portion 24 and via at least one hole 25 in thedistribution piece 18. The hole 25 is of such dimensions that a definedapportioning of the hot steam 10 to two partial flows is carried out,specifically once via the hole 25 to the discharge opening 60 of thecentral nozzle 62 and once via the annulus of the annular slot nozzle 31to the annular slot 29 at the nozzle mouth.

In the depicted embodiment of the nozzle 1, the central nozzle piece 27is screwed into the distribution piece 18 and forms the central nozzle62 for the central steam jet 28. A flow path of the central nozzle 62then extends to the central chamber in the distribution piece 18 firstof all convergently in a first conically tapering section. A cylindricalsection adjoins this first conically tapering section, forming aconstriction. Adjoining this, a conically widening section to thedischarge opening 60 follows. As is customary in Laval nozzles, thecentral nozzle 62 therefore extends first of all convergently and thendivergently, and the cross-sectional dimensions of the central nozzle 62are also responsible for the distribution of the steam flow 10 to thecentral nozzle 62 and to the outer annular gap nozzle 31. The outersteam flow, also referred to as annular slot steam flow 30, is fed viathe milled out portion 24 first of all to the annulus of the annularslot nozzle 31 and from here finds its way into the outer annular slot29. The steam therefore discharges both as a central steam jet 28 fromthe central nozzle 62 and from the outer annular slot 29.

The outer annular slot 29 is formed between an outer cap 49 and theintermediate cap 34. The steam, at high velocity right up to highsupersonic velocities, discharges from the outer annular slot 29 andfrom the discharge opening 60, as is illustrated by arrows 32, 33 inFIG. 2. As a result of the interaction between the ring-like fluid jet,which discharges from the first annular slot 21, and the flanking steamjets according to the arrows 32 and 33, a droplet spray jet with theboundary 22 is created, as is shown by the dashed lines in FIG. 1.

In many cases, the previously described configuration should alreadyeffect an adequate thermal decoupling of hot steam 10, as atomizing gas,and the cold fluid 5 to be atomized. In order to improve such a thermaldecoupling and to reduce a heat transfer between fluid 5 to be atomizedand the hot steam 10, the connecting line 4 for the fluid 5 is ofdouble-walled design in which provision is made for an inner tube 37 upto the connection to the distribution piece 18. The connecting line 4 istherefore of double-walled design and provided with a thermallyinsulating air gap 44. Alternatively, the connecting line can also beconstructed with a graphite sleeve in order to achieve a thermalinsulation.

In addition, the flow passage in the at least one hole 19 in thedistribution piece 18 for the feed of water to the annulus of theannular slot nozzle 20 is also of double-walled design with the innertube 38, wherein, as was explained, an air gap lies between the innertube 38 and the hole 19 in the distribution piece 18.

The water-conducting annulus of the annular slot nozzle 20 is thermallyinsulated by layers 35, 36 of suitable material towards the centralnozzle piece 27 as well as towards the intermediate cap 34. Theseinsulating layers 35, 36 for example can consist of metal with poorthermal conductivity or from a ceramic material.

In order to further reduce the heat transfer between fluid 5 and hotsteam 10, a disk 40 produced from a thermally insulating material isprovided on a bottom face 39 of the distribution piece 18 to which theconnecting line 4 for fluid 5 is attached. As a result, a heat transferof from the fluid 5 in the connecting line 4 to the distribution piece18 can be significantly reduced. The disk 40 is provided withthrough-holes in order to direct fluid 5 into the at least one hole 19or into the inner tube 38 in the distribution piece 18.

To which extent the previously described measures are adopted dependsupon the operating conditions of the nozzle. Already by the provision ofthe distribution piece 18 in the housing 2 of the nozzle 1, in manycases an adequate thermal decoupling of hot steam 10 and fluid 5 to beatomized is already achieved so that as a rule such costly additionalinsulation measures can be dispensed with.

The nozzle housing 2 is of multi-piece design and has a first,approximately cup-shaped component 64 having the connecting line 11 forhot steam and having the connection 17 for the connecting line 4 forfluid 5. The distribution piece 18 is inserted into the cup-shapedcomponent 64 and is screwed onto the connecting line 4, which is alsoinserted into the component 64, and is supported in the radial directionon the inner wall of the cup-shaped component 64 via ribs 66. Provisionis made between the ribs 66 for the milled-out portions 24 via which hotsteam 10 finds its way into the flow passage, formed by the hole 25, inthe distribution piece 18 and to the outer annular slot 31.

The outer cap 49 is screwed onto the cup-shaped component 64. Arrangedinside the outer cap 49 is the intermediate cap 34 which is screwed ontothe distribution piece 18. The outer annular slot nozzle 31 for hotatomizing gas is therefore formed between the outer cap 49 and theintermediate cap 34 and ends at the nozzle mouth on the outer annularslot 29.

Inside the intermediate cap 34, the central nozzle piece 27 is screwedinto the distribution piece 18. The annular slot nozzle 20 for fluid tobe atomized is formed between the central nozzle piece 27 and theintermediate cap 34 and ends at the nozzle mouth on the annular slot 21.As was previously described, an outer side of the central nozzle piece27, which delimits the annular slot nozzle 20 on one side, is lined, atleast in sections, with an insulating layer 35. Only directly upstreamof the annular slot 21 is there no longer provision for an insulatinglayer 35 in order to be able to design the annular slot 21 narrow.

An inner side of the intermediate cap 34, which outwardly delimits theannular slot nozzle 20, is also lined in sections with an insulatinglayer 36. Only directly upstream of the annular slot 21 is there nolonger provision for an insulating layer 36.

The nozzle 1 according to the invention is obviously of a very compactconstruction and particularly effects a distribution of the hot steam 10to the central nozzle 62 and to the outer annular slot nozzle 31 insidethe housing 2 of the nozzle 1 over a short distance. The flow passagefor hot steam in the distribution piece 18, formed by the hole 25, viawhich hot steam finds its way to the central nozzle 62, is arranged atan angle to the flow passage for fluid 5 to be atomized—also provided inthe distribution piece 18—which is formed by the hole 19 and the innertube 38. The flow passage for hot steam and the flow passage for fluidare therefore arranged inside the distribution piece 18 in a crosswisemanner. In the depicted embodiment, an angle of about 45° lies betweenthe center longitudinal axes of the flow passage for hot steam and ofthe flow passage for fluid.

The distribution piece 18 is produced from high-alloy high-grade steelwhich has low thermal conductivity. Compared with conventional brassnozzles, a heat transfer from the hot steam 10 to the cold fluid 5,which is reduced by a factor of about 8, is already achieved as aresult.

The inner tube 38, which is inserted into the hole 19 of thedistribution piece 18, forms a flow passage for the fluid 5 through thedistribution piece 18. The inner tube 38 is constructed as a turned partand bears against the inner wall of the hole 19 only in the regions 68,70. Outside the regions 68, 70, which are shown in black in FIG. 1, aninsulating air gap 72 lies between the inner tube 38 and thedistribution piece 18.

FIG. 2 shows the nozzle mouth having the discharge opening 60 of thenozzle 1 in an enlarged view. It is to be seen that the dischargeopening 60 of the central nozzle 62, the end of the annular slot 21 ofthe annular slot nozzle 20, and the annular slot 29 which defines theoutlet of the annular slot nozzle 31, are located exactly at the sameheight, as seen transversely to the flow direction. Consequently, mixingof the hot steam jets from the annular slot nozzle 31 and from thecentral nozzle 62 with the annular slot flow of fluid to be atomizedfrom the annular slot nozzle 20 is carried out just outside the nozzle1.

The view of FIG. 3 shows a further multi-component nozzle 80 accordingto the invention according to a second preferred embodiment. Themulti-component nozzle 80 is to a great extent constructed identicallyto the multi-component nozzle 1 in FIG. 1 so that only the featureswhich differ from the nozzle 1 in FIG. 1 are explained.

As is to be seen in FIG. 3, a central body 41, which extends through acentral nozzle 82 for hot steam, is screwed into the distribution piece18. The central body 41 is therefore completely exposed to circumflow byhot steam from the central chamber 26 in the distribution piece 18. Inthe region of the discharge opening 60, the central body is designed inthe form of a widening cone 42 so that the discharge opening 60 is ofring-like design and an inner annular slot 43 is formed for thedischarge of the proportion of hot steam 10 which is fed via the hole25. The ring-like flow of fluid 5 to be atomized is therefore enclosedbetween two also ring-like hot steam flows.

By providing the cone 42, the central steam also discharges via theannular slot 43. The central cone 42 in this case, however, is onlyexposed to circumflow by hot steam which is free of solids as far aspossible so that no relevant risk of deposits forming on the cone 42exists. As a result of the cone 42, the steam consumption of the nozzle80 can be reduced a little more compared with the nozzle 1 without thishaving a negative effect upon the atomization quality. Also, in the caseof the nozzle 80 having the central cone 42, the central nozzle 82 canbe constructed as a Laval nozzle. This, however, is not the case in theview of FIG. 3. In order to form the central nozzle 82 as a Lavalnozzle, the flow cross section of the annular slot between the centralbody 41 and the discharge section of the central nozzle 82 must have adivergent progression towards the nozzle mouth.

The view of FIG. 4 shows section-wise a multi-component nozzle 90according to the invention according to a third preferred embodiment.The nozzle is formed to a great extent identically to the nozzle 1 inFIG. 1 so that only the features which differ from the nozzle 1 aredescribed.

The nozzle 90 has an outer cap 92 which is extended compared with theouter cap 49 of the nozzle 1. As a result, the discharge opening 60 ofthe central nozzle 62 and the annular slot 21 of the annular slot nozzle20 for fluid to be atomized are set back in relation to the nozzlemouth. The nozzle mouth is formed in this case by thedownstream-disposed end of the outer cap 92. In the case of the nozzle90, contact consequently already occurs inside the nozzle housingbetween the ring-like fluid flow from the annular slot 21 and the hotgas flows from the discharge opening 60 and from the annular slot 29.Already created inside the nozzle housing as a result, albeit close tothe nozzle mouth, is a free fluid lamella which is no longer braked as aresult of wall friction but sharply accelerated by means of the flankinghigh-velocity flows of auxiliary atomizing medium, for example hotsteam. To already implement this inside the nozzle 90 offers theadvantage that here the flows of the auxiliary atomizing medium andespecially the hot gas flow from the annular slot 29 cannot yet deviateto the side, as is the case after leaving the nozzle. In this way, aneven finer atomization of the fluid is brought about. The setting backof the outlet of the fluid nozzle in relation to the position of thenozzle mouth is advantageously one to ten times the width of the annularslot 21 of the annular slot nozzle 20 for the fluid at the nozzle mouth.In the depicted, purely exemplary drawing, the width of the annular slot21 for the fluid is about 1 mm and this annular slot is set back inrelation to the nozzle mouth by about 5 mm, that is to say five timesthe width of the annular slot 21.

With the invention, provision is therefore made for an externally mixingmulti-component nozzle in which a minimum internal heat transfer betweenthe fluid to be sprayed and the atomizing gas is realized. Thedistribution of the fluid to be atomized and of the atomizing gas isundertaken in a distributor which is integrated into the nozzle body orthe nozzle housing. The effect achieved as a result of this designaccording to the invention is that the heat transfer from the hotatomizing gas to the fluid to be atomized inside the nozzle, especiallyinside the nozzle housing, is minimized or limited to an advantageousvalue. The externally mixing multi-component nozzles according to theinvention are used in flue gas ducts or in flue gas scrubbing plants inpower plants or in the cement industry.

1. An externally mixing multi-component nozzle for spraying fluids withthe aid of an atomizing gas, especially steam or hot gas, which is hotin relation to the fluids to be atomized, with a housing, wherein thehousing has a discharge opening for the atomizing gas, a first annularslot, encompassing the discharge opening, for fluid to be atomized, anda second annular slot, encompassing the first annular slot, for theatomizing gas, and also a distribution piece, wherein the distributionpiece has at least one flow passage for fluid to be atomized from aconnecting line to the first annular slot and at least one flow passagefrom an atomizing gas connecting line to the discharge opening foratomizing gas.
 2. The externally mixing multi-component nozzle asclaimed in claim 1, wherein the housing has an annular passage foratomizing gas which encompasses the distribution piece at least insections.
 3. The externally mixing multi-component nozzle as claimed inclaim 2, wherein the flow passage of the distribution piece for theatomizing gas originates from the annular passage.
 4. The externallymixing multi-component nozzle as claimed in claim 1, wherein a thermalinsulation is provided, at least in sections, between the flow passagefor fluid to be atomized and the distribution piece.
 5. The externallymixing multi-component nozzle as claimed in claim 4, wherein the flowpassage for fluid to be atomized is formed, at least in sections, bymeans of a tube which is inserted into the distribution piece.
 6. Theexternally mixing multi-component nozzle as claimed in claim 5, whereinan air gap is provided, at least in sections, between the tube and thedistribution piece.
 7. The externally mixing multi-component nozzle asclaimed in claim 1 wherein the connecting line for fluid to be atomizedis of double-walled design at least in the connecting region to thedistribution piece.
 8. The externally mixing multi-component nozzle asclaimed in claim 1, wherein a thermal insulating layer is providedbetween the first annular slot and the housing and also between thefirst annular slot and the second annular slot.
 9. The externally mixingmulti-component nozzle as claimed in claim 1, wherein the dischargeopening for atomizing gas has the form of a third annular slot.
 10. Theexternally mixing multi-component nozzle as claimed in claim 1, whereinthe boundary of the first annular slot, as seen in the flow direction,is arranged in front of an outer boundary of the second annular slot 11.The externally mixing multi-component nozzle as claimed in claim 10,wherein the boundary of the first annular slot is arranged by one to tentimes the width of the first annular slot in front of the outer boundaryof the second annular slot, as seen in the flow direction.
 12. Theexternally mixing multi-component nozzle as claimed in claim 1, whereinat least the distribution piece is formed from a material, especiallyhigh-alloy high-grade steel, with a coefficient of thermal conductivitywhich is significantly reduced, especially by the factor of 8, comparedwith brass.
 13. The externally mixing multi-component nozzle as claimedin claim 1, wherein a section—g directly upstream of the dischargeopening—of the flow passage for atomizing gas in the housing first ofall tapers and after passing a constriction widens again up to thedischarge opening, as seen in the flow direction.